(1R,5S)-tert-butyl 3-(trifluoromethylsulfonyloxy)-8-azabicyclo[3.2.1]oct-2-ene-8-carboxylate

37595-74-7

185099-67-6

185099-68-7

To a solution of tert-butyl 3-oxo-8-azabicyclo[3.2.1]octane-8-carboxylate (1.0 g, 4.2 mmol) in tetrahydrofuran (21.1 mL) was added slowly and dropwise lithium hexamethyldisilanilaminate (LHMDS, 4.64 mL, 4.64 mmol) under nitrogen atmosphere. The temperature of the reaction system was maintained at -50 °C, followed by a slow warming to -30 °C and continuous stirring for 1 hour. A solution of N-phenylbis(trifluoromethanesulfonyl)imide (1.66 g, 4.64 mmol) in tetrahydrofuran (1.0 mL) was added dropwise to the reaction mixture at -30 °C. After the dropwise addition was completed, the reaction mixture was gradually warmed to 25 °C and stirring was continued for 4 hours. Upon completion of the reaction, the reaction was quenched by the addition of aqueous ammonium chloride solution (10 mL), followed by extraction of the aqueous layer with dichloromethane (3 x 10 mL). The organic layers were combined, dried with anhydrous sodium sulfate, filtered and concentrated under reduced pressure. The residue was purified by silica gel column chromatography (eluent: 0-30% ethyl acetate/hexane) to afford the target product 8-Boc-3-(trifluoromethylsulfonyloxy)-8-azabicyclo[3.2.1]oct-3-ene (2.2 g, 95% yield). Mass spectrometry (electrospray positive ion mode) analysis result: C13H18F3NO5S theoretical molecular weight 357, measured value 358 [M+H]+.